Depending on the processed material from each drill must be properly sharpened. To verify the correct angle will help a specially prepared square plate of copper or aluminium with a thickness of 1 mm.
To become operational protractor enough to cut it cut, as shown in the picture: a large cutout at an angle of 120 degrees, the other half is 60 degrees and the surviving corner of a square is 90.
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MATCHBOX “ELEVATOR”
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NEITHER OF PELINCE, NOT A SPECK OF DUST
To save yourself from cleaning sawdust, dust after drilling in the wall, before beginning work, secure the paper on the sticky tape just below future openings.